Essential tremor is a hereditary type of hyperkinesis, manifested by kinetic and postural trembling of the hands, head, lower jaw, lips, eyelids, vocal cords, less often — legs, trunk. It is diagnosed mainly clinically. The exclusion of secondary tremors is carried out with the help of biochemical analyses, hormonal studies, MRI and CT of the brain, examination of cerebral vessels, electroneurography. Therapy is carried out with beta-blockers, anticonvulsants, high dosages of vitamin B6, acupuncture. It is possible to use targeted deep stimulation of extrapyramidal system structures.
ICD 10
G25.0 Essential tremor
General information
Essential tremor was described in detail by L. S. Minor in 1929. The author emphasized the distinctive feature of this type of tremor – the manifestation of muscle tension and movement. Noted the hereditary nature of the disease. Today, literary sources on neurology mention pathology with synonymous names: Minor’s disease, hereditary tremor.
The incidence of pathology increases with age. According to various data, essential tremor is observed in 0.3-6.7% of people under 40 years of age, and in 8-17% after 70 years of age. Morbidity statistics do not give exact figures, since the goodness of tremor leads to a reduced patient referral to doctors. There are also diagnostic errors — sometimes shaking is regarded as Parkinson’s disease.
Essential tremor causes
The etiology of the disease is closely related to genetic disorders transmitted in an autosomal dominant way. If one parent suffers from tremor, the probability of its development in a child is at least 50%. Along with cases with clearly traceable heredity, there are many sporadic forms when such pathology is not detected among the relatives of the patient.
Recent advances in genetics have made it possible to determine that several genes are responsible for the development of hereditary tremor. Two are located at the q13 locus of the 3rd chromosome, one is on the short arm of the 2nd chromosome. Apparently, gene aberrations lead to disorders in the extrapyramidal system responsible for the regulation of posture, muscle tone. The morphological structures of this system are the thalamus and subcortical nodes, but degenerative changes in them are detected on MRI only in individual patients.
Essential tremor symptoms
The main clinical manifestation is a small—scale tremor, the frequency of which varies from 6 to 12 Hz. The brushes are most often subject to shaking. It is clearly noticeable when stretching the arms in front of you and holding them in this position (postural tremor). Intentional tremor is also characteristic – trembling during purposeful movements. In some cases, the trembling phenomenon is observed at rest. In all patients, these changes completely disappear during sleep. Physical exertion and emotional experiences can enhance tremor.
Essential tremor can cover the head, chin, lips, tongue. Tremor of the vocal cords causes the voice to vibrate, disrupts the clarity of speech. Trembling of the legs and torso is less common. Light changes do not particularly affect the quality of life. Moderate tremor of the upper extremities complicates small work and leads to a change in handwriting: the letters become pointed, there are no connections between them. Pronounced trembling reduces performance and can cause disability. A tremor noticeable to others causes psychological discomfort. It is possible to develop suspiciousness, depressive neurosis, hypochondria.
For a long time, essential tremor was considered a monosymptomatic disease. Recently, clinicians have been talking about the presence of clinical forms accompanied by other neurological symptoms, mental and cognitive changes. There are ataxia, hearing loss, depression, phobic disorders, decreased memory, attention. However, it should be borne in mind that in elderly patients, this symptomatology is often caused by dyscirculatory encephalopathy with chronic cerebral circulatory insufficiency, age-related degenerative processes.
Diagnostics
Essential tremor is diagnosed only after excluding all possible causal diseases and is based mainly on the features of the clinical picture and anamnestic data. The diagnostic process takes place in several stages.
- Consultation with a neurologist. A study of the neurological status of the patient, an analysis of his mental state, an examination of the neck for changes from the thyroid gland is carried out. Physical examination helps to determine the time of occurrence and the nature of the trembling phenomenon, the sequence of involvement of various parts of the body in it. Objectively, a neurological examination reveals trembling of the fingers and hands in the Romberg pose, when performing a finger-nasal test. Trembling of the lower extremities is determined when performing a knee-heel test. In a relaxed comfortable position of the body, it disappears.
- MRI of the brain or CT. The study visualizes brain structures and various cerebral lesions (tumors, degenerative changes, atrophic areas, signs of encephalitis, etc.).
- Ultrasound diagnostics. Ultrasound and duplex scanning of cerebral vessels help to assess the state of cerebral circulation. Ultrasound of the thyroid gland is performed according to indications, it can be supplemented with a consultation of an endocrinologist.
- Electroneurography — allows you to exclude polyneuropathy.
- Laboratory tests: biochemical blood test, thyroid function study, determination of parathyroid hormone level.
- Consultation of a geneticist and genealogical research is required to confirm the genetic nature of the disease. The presence in the anamnesis of relatives with similar symptoms indicates in favor of hereditary tremor.
Differential diagnosis
The diagnosis of “essential tremor” is established after the exclusion of the physiological nature of the tremor and its connection with other diseases. Differential diagnosis is performed with tremor when:
- nervous system lesions (parkinsonism, encephalitis, brain tumors, consequences of stroke, traumatic brain injury, multiple sclerosis, polyneuropathy, cerebellar diseases);
- endocrine disorders (hyperthyroidism, hyperparathyroidism, hypoglycemia);
- intoxication (alcoholism, uremia with renal insufficiency);
- mental disorders (neurasthenia, hysteria);
- side effects of some pharmaceuticals.
Trembling phenomena that occur against the background of the underlying pathology are usually combined with typical symptoms for it. Psychogenic tremor is caused by stress, experiences, mental abnormalities. Parkinsonism is characterized by rest trembling, accompanied by bradykinesia, muscle rigidity. Cerebellar ataxia is diagnosed by a characteristic gait, large-scale handwriting, hypermetry of movements. But we must not forget that two diseases are possible in one patient (for example, essential tremor and Parkinson’s disease). The acute onset and the connection with the provoking factor (stress, TBI, taking a pharmacological drug) confirms the secondary nature of the tremor.
Essential tremor treatment
Conservative therapy
Therapy is aimed at reducing trembling and slowing the progression of the disease. It has been held for years. It includes pharmacotherapy, relaxing massage, acupuncture. Patients are not recommended for increased physical and psycho-emotional stress. In drug treatment, the drugs of choice are:
- Beta-blockers (propanolol) — have a good effect. They are prescribed for a long time with mandatory monitoring of blood pressure and pulse.
- Anticonvulsants. Primidone, clonazepam, was previously successfully used. Now promising are new generation antiepileptic drugs, namely levetiracetam. Prevention of side effects (drowsiness and asthenia) is achieved by gradual careful dose selection.
- Pyridoxine — high doses of vitamin B6 contribute to a significant slowdown in the progression of the disease. The drug is administered intramuscularly. The course of treatment lasts 1 month, is repeated 2-3 times annually.
When the head is shaking, therapy is possible by injecting botulinum toxin into the nodding muscles. The effect of the injection lasts up to 2.5 months, then a repeat procedure is required.
Neurosurgical methods
Pronounced essential tremor, resistant to conservative therapies, may be an indication for alternative treatments, such as deep cerebral stimulation. Electrodes are implanted intracranially, connected to a small device that sends tremor-suppressing impulses. Recently, a group of researchers has developed a method of ablation of certain areas of the thalamus passing through the bones of the skull with targeted ultrasound radiation. Developments in this direction are continuing.
Forecast
As a rule, essential tremor has a benign course, responds well to treatment. Some patients do not turn to doctors for a long time, because they experience only minor inconveniences. In the absence of therapeutic measures, progression usually occurs, which can accelerate in old age. Pronounced tremor reduces the quality of life and ability to work, makes it difficult to self-care, has a bad effect on psychological well-being.
